This can happen because the display resolution that you have set it is not the right one for your screen.
To solve this, click your name on the top bar and go to
Would like a little more explanation on native resolution, which is generally only applicable on LCDs. There's a stub for using two monitors. Link from section below when it's added.
If you have two displays connected to the computer (for example, a normal monitor and a projector), the displays might have different resolutions. However, the computer's graphics card can only display the screen in one resolution at a time, so at least one of the displays might look fuzzy.
You can set it so that the two displays have different resolutions, but you won't be able to display the same thing on both screens simultaneously. In effect, you will have two independent screens connected at the same time. You can move windows from one screen to another, but you can't show the same window on both screens at once.
To set-up the displays so that they each have their own resolution:
Click your name on the top bar and click
Uncheck
Select each display in turn from the gray box at the top of the